Is the 12-40mm good enough to forego 12mm, 17mm, 25mm and 45mm primes?

I went back and looked at a lot of my shots, and I had an acceptable amount of blur. Like others have mentioned, when I used the 50mm 1.8 on the Canon, I'd get the nose in focus and the rest of the child pleasingly blurry! That's not what I intended. More like, the swing set blurry and the child's head in focus. While its easy for this to happen with the Canon setup, it take more finesse to work DOF with MFT.